FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person *   MPM BioVentures IV QP LP 2. Date of Event Requiring Statement (Month/Day/Year) 05/30/2013 3. Issuer Name and Ticker or Trading Symbol Epizyme, Inc. [EPZM] (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT, 200 CLAREDON STREET, 54TH FLOOR 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) BOSTON, MA 02116 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5) Common Stock 178,331 (1) I See Footnote (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A Preferred Stock	  (3)	  (3)	Common Stock	2,309,998	$ (3)	I	See Footnote (4)
Series B Preferred Stock	  (5)	  (5)	Common Stock	392,156	$ (5)	I	See Footnote (6)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MPM BioVentures IV QP LP C/O MPM ASSET MANAGEMENT 200 CLAREDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â
Scopa James Paul C/O MPM ASSET MANAGEMENT 601 GATEWAY BLVD., SUITE 350 SOUTH SAN FRANCISCO, CA 94080	Â	  X	Â	Â
Vander Vort John C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â
MPM Asset Management Investors BV4 LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â
MPM BioVentures IV GmbH & Co. Beteiligungs KG C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â
MPM BioVentures IV GP LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â
MPM BioVentures IV Strategic Fund, L.P. C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â
MPM BioVentures IV LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â
Foley Todd C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â
KAILIAN VAUGHN M C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116	Â	  X	Â	Â

Signatures

By Luke Evnin, member of MPM BioVentures IV LLC, the managing member of MPM BioVentures IV GP LLC, the general partner of MPM BioVentures IV-QP, L.P. /s/ Luke Evnin		05/30/2013
**Signature of Reporting Person		Date
/s/ James P. Scopa		05/30/2013
**Signature of Reporting Person		Date
/s/ John Vander Vort		05/30/2013
**Signature of Reporting Person		Date
By Luke Evnin, member of MPM BioVentures IV LLC, the manager of MPM Asset Management Investors BV4 LLC /s/ Luke Evnin		05/30/2013
**Signature of Reporting Person		Date
By Luke Evnin, member of MPM BioVentures IV LLC, the managing member of MPM BioVentures IV GP LLC, the managing limited partner of MPM BioVentures IV GmbH & Co. Beteiligungs KG /s/ Luke Evnin		05/30/2013
**Signature of Reporting Person		Date
By Luke Evnin, member of MPM BioVentures IV LLC, the managing member of MPM BioVentures IV GP LLC /s/ Luke Evnin		05/30/2013
**Signature of Reporting Person		Date
By Luke Evnin, member of MPM BioVentures IV LLC, the managing member of MPM BioVentures IV GP LLC, the general partner of MPM BioVentures IV Strategic Fund, L.P. /s/ Luke Evnin		05/30/2013
**Signature of Reporting Person		Date
By Luke Evnin, member of MPM BioVentures IV LLC /s/ Luke Evnin		05/30/2013
**Signature of Reporting Person		Date
/s/ Todd Foley		05/30/2013
**Signature of Reporting Person		Date
/s/ Vaughn Kailian		05/30/2013
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Reflects a one-for-three reverse stock split effected May 13, 2013.
(2)	The shares are held as follows: 166,007 by MPM BioVentures IV-QP, L.P. ("BV IV QP"), 6,395 by MPM BioVentures IV GmbH & Co. Beteiligungs KG ("BV IV KG"), 4,720 by MPM Asset Management Investors BV4 LLC ("AM BV4") and 1,209 shares held by MPM BioVentures IV Strategic Fund, L.P. ("BV IV SF"). MPM BioVentures IV GP LLC and MPM BioVentures IV LLC ("BV LLC") are the direct and indirect general partners of BV IV QP, BV IV KG and BV IV SF and BV LLC is the manager of AM BV4. Ansbert Gadicke, Luke Evnin, Vaughn M. Kailian,James Paul Scopa, Todd Foley and John Vander Vort are the members of BV LLC. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.
(3)	Each share of Series A Preferred Stock is convertible into 1/3rd of a share of Common Stock without payment of further consideration and will automatically convert into 1/3rd of a share of Common Stock upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date.
(4)	The shares are held as follows: 1,850,799 by BV IV QP, 71,303 by BV IV KG, 52,628 by AM BV4 and 335,268 shares held by BV IV SF. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.
(5)	Each share of Series B Preferred Stock is convertible into 1/3rd of a share of Common Stock without payment of further consideration and will automatically convert into 1/3rd of a share of Common Stock upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date.
(6)	The shares are held as follows: 312,152 by BV IV QP, 12,026 by BV IV KG, 8,876 by AM BV4 and 59,102 shares held by BV IV SF. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.
  Remarks: See Form 3 for Luke Evnin for additional members of this joint filing.

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